231 publications from this institution
This study investigates the maximum usable strain and the progressive failure of FRP-confined concrete. Ten FRP-confined concrete specimens were divided into two groups with different jacket stiffness. One specimen in each group was tested until failure while the others were loaded to target strains and then unloaded in order to monitor the residual strength of the concrete cores. At 1% axial strain of FRP-confined concrete, the residual strength of the concrete cores were reduced more than 56% compared to the reference specimens. Experimental results have shown that the maximum usable strain of 1% is un-conservative for FRP-confined concrete. The residual strength of the column cores is equal to the ordinate of the intersection between the unload curve and the unconfined concrete curve. The maximum usable strain of FRP-confined concrete is not a constant. It depends on the unconfined concrete strength and the jacket stiffness.
Abstract Utilization of industrial by‐products in concrete is an effective way to reduce the exhaustion of raw materials for concrete production, but it can lead to degradation in concrete properties. Therefore, research efforts are required to achieve a balance between waste utilization and concrete performance. This study examined the strength and durability performance of geopolymer concrete (GPC) developed from fly ash (FA) and fine rice husk ash (FRHA) as main binders (50/50), with partial OPC substitution at different levels (0%–30%). Various properties like workability, compressive strength, water absorption, chloride penetration resistance, carbonation depth, electrical resistivity (ER), and acid attack resistance were experimentally investigated. Results indicated that there was a noticeable improvement in the workability with 20% OPC substitution, achieving the highest slump of 110 mm. The highest compressive strength (50 MPa) was attained with 15% OPC substitution after 90 days. Mix FR85C15 (15% OPC replacement) showed the highest durability performance at all ages through various indicators, that is, water absorption, charge passed, carbonation depth, and ER. Scanning electron microscopy and energy dispersive spectroscopy analyses also validated the enhanced microstructure of FR85C15 compared with other mixes. When exposed to sulfuric acid (H 2 SO 4 ), Mix FR85C15 showed a minimal loss of 14% in compressive strength. It was concluded that GPC produced using FA and FRHA substituting OPC (up to 15%) can potentially be utilized for structural applications.
A new model is presented for calculating the axial strain of carbon fiber-reinforced polymer (CFRP)-confined concrete columns. An energy-balance approach is introduced to establish a relationship of the energy absorption between a confined concrete column and CFRP. The proposed model was verified using a large database collected from 167 CFRP-confined plain concrete specimens. This database contains 98 circular specimens with diameters ranging between 100 and 152 mm, and 69 square specimens having a side length ranging between 100 and 152 mm. The database covers unconfined concrete strengths from 20 to 50 MPa. The proposed model shows very good correlation with the experimental results. In addition, the proposed model also provides a comparative prediction of the strain of CFRP-confined concrete columns in two extreme cases, i.e., (1) insufficient confinement, and (2) heavy confinement, which are not usually well predicted by other models.
Due to its distinctive institutional background, Oman offers a valuable opportunity to investigate the stability of the dividend policy. In Oman, (1) there are no taxes on dividends, (2) firms are highly levered mainly through bank loans, (3) there is a high concentration of stock ownership and (4) there is variability in cash dividend payments. These factors suggest a diminished role of dividend smoothing in Oman. Our results show that Omani financial firms have erratic dividend policies. These results are inconsistent with the predictions suggested by the relatively weak corporate governance, government ownership and dividend signalling.
